Processor or main modules are known and are distributed, for example, by the National Semiconductor Corporation under the family designation MA2000. The processor modules are of different types such as microcomputer modules, memory modules, analog modules and the like. Each processor module comprises a circuit board or plate which is provided with integrated and printed circuits as well as other components. The electrical and mechanical connections between the processor modules are established by way of pluggable bus-coupled connections. Such connections typically employ two connectors mounted adjacent longitudinal edges of rectangular processor modules. Peripheral connections formed with laterally projecting connectors can be provided along narrow sides of the processor modules.
The above-described design of processor modules renders it possible to assemble a wide variety of electrical devices from a limited number of modules. The connectors between neighboring modules form a continuous bus of conductors such as for data transmission, control, power supply and other functions. There is no need to provide a separate bus. However, such design is suitable only for modules which need to be connected to the same bus.